2,5-disubstituted 3-mercaptopentanoic acid

ABSTRACT

The present invention concerns compounds of formula (I), and pharmaceutically acceptable salts or solvates thereof, or solvates of such salts, which compounds inhibit carboxypeptidase U and thus can be used in the prevention and treatment of diseases where inhibition of carboxypeptidase U is beneficial. In further aspects, the invention relates to compounds of the invention for use in therapy; to processes for preparation of such new compounds; to pharmaceutical compositions containing at least one compound of the invention, or a pharmaceutically acceptable salt or solvate thereof, as active ingredient; and to the use of the active compounds in the manufacture of medicaments for the medical use indicated above.

The present invention relates to novel compounds, and pharmaceuticallyacceptable salts thereof, which inhibit basic carboxypeptidase, morespecifically carboxypeptidase U, and thus can be used in the preventionand treatment of diseases wherein inhibition of carboxypeptidase U isbeneficial, such as thrombosis and hypercoagulability in blood andtissue, atherosclerosis, adhesions, dermal scarring, cancer, fibroticconditions, inflammatory diseases and those conditions which benefitfrom maintaining or enhancing bradykinin levels in the body. In furtheraspects, the invention relates to compounds of the invention for use intherapy; to processes for preparation of such new compounds; topharmaceutical compositions containing at least one compound of theinvention, or a pharmaceutically acceptable salt thereof, as activeingredient; and to the use of the active compounds in the manufacture ofmedicaments for the medical use indicated above.

Fibrinolysis is the result of a series of enzymatic reactions resultingin the degradation of fibrin by plasmin. The activation of plasminogenis the central process in fibrinolysis. The cleavage of plasminogen toproduce plasmin is accomplished by the plasminogen activators,tissue-type plasminogen activator (t-PA) or urokinase-type plasminogenactivator (u-PA). Initial plasmin degradation of fibrin generatescarboxy-terminal lysine residues that serve as high affinity bindingsites for plasminogen. Since plasminogen bound to fibrin is much morereadily activated to plasmin than free plasminogen this mechanismprovides a positive feedback regulation of fibrinolysis.

One of the endogenous inhibitors to fibrinolysis is carboxypeptidase U(CPU). CPU is also known as plasma carboxypeptidase B, active thrombinactivatable fibrinolysis inhibitor (TAFIa), carboxypeptidase R andinducible carboxypeptidase activity. CPU is formed during coagulationand fibrinolysis from its precursor proCPU by the action of proteolyticenzymes, such as thrombin, thrombin-thrombomodulin complex or plasmin.CPU cleaves basic amino acids at the carboxy-terminal of fibrinfragments. The loss of carboxy-terminal lysines and thereby of lysinebinding sites for plasminogen then serves to inhibit fibrinolysis. Byinhibiting the loss of lysine binding sites for plasminogen and thusincrease the rate of plasmin formation, effective inhibitors ofcarboxypeptidase U are expected to facilitate fibrinolysis.

2-Mercaptomethyl-3-guanidinoethylthiopropanoic acid is reported as acarboxypeptidase N inhibitor. More recently, this compound has beenshown to inhibit CPU, Hendriks, D. et al., Biochimica et BiophysicaActa, 1034 (1990) 86-92.

Guanidinoethylmercaptosuccinic acid is reported as a carboxypeptidase Ninhibitor. More recently, this compound has been shown to inhibit CPU,Eaton, D. L., et al., The Journal of Biological Chemistry, 266 (1991)21833-21838.

CPU inhibitors are disclosed in WO 00/66550, WO 00/66557, WO 03/013526and WO 03/027128 and a pharmaceutical formulation containing a CPUinhibitor and a thrombin inhibitor is disclosed in WO 00/66152.Inhibitors of plasma carboxypeptidase B are disclosed in WO 01/19836.Inhibitors of TAFIa are disclosed in WO 02/14285.

It has now been found that compounds of formula (I) are particularlyeffective as inhibitors of carboxypeptidase U and are thereby useful asmedicaments for the treatment or prophylaxis of conditions whereininhibition of carboxypeptidase U is beneficial.

Thus, the present invention provides a compound of formula (I):

wherein:R¹ is phenyl {optionally substituted by halogen, hydroxy, cyano, C₁₋₄alkyl (itself optionally mono-substituted by cyano, hydroxy or phenyl),C₁₋₄ alkoxy (itself optionally substituted by tetrahydrofuranyl), CF₃,OCF₃, methylenedioxy, C(O)R³, S(O)₂R⁴, phenyl (itself optionallysubstituted by halogen), phenoxy (itself optionally substituted byhalogen) or tetrahydrofuranlyoxy}, naphthyl, pyridinyl,1,2,3,4-tetrahydropyrimidin-2,4-dione-yl (optionally substituted by C₁₋₄alkyl) or tetrahydrothienyl;R² is aminopyridinyl, aminothiazolyl or 3-azabicyclo[3.2.1]octyl;R³ is hydroxy, C₁₋₄ alkoxy (itself optionally substituted by phenyl(itself optionally substituted by halogen) or pyridinyl), NR⁵R⁶ or anN-linked 5- or 6-membered heterocyclic ring {unsubstituted ormono-substituted by hydroxy, oxo, C₁₋₄ alkyl (itself optionallysubstituted by hydroxy or NHphenyl), CO₂(C₁₋₄ alkyl) or phenyl (itselfoptionally substituted by halogen)};R⁴ is NR⁷R⁸ or an N-linked 5- or 6-membered heterocyclic ring{unsubstituted; mono-substituted by hydroxy, oxo, C₁₋₄ alkyl (itselfoptionally substituted by hydroxy or NHphenyl), CO₂(C₁₋₄ alkyl) orphenyl (itself optionally substituted by halogen); or fused to a benzenering which is optionally substituted by C₁₋₄ alkoxy};R⁵, R⁶, R⁷ and R⁸ are, independently, hydrogen, C₁₋₄ alkyl {optionallysubstituted by halogen, cyano, hydroxy, phenyl (itself optionallysubstituted by halogen or methylenedioxy), pyridinyl, CO₂H or CO₂(C₁₋₄alkyl)} or C₂₋₄ alkenyl; provided that when R¹ is 6-aminopyridin-3-ylthen R² is substituted phenyl, naphthyl, pyridinyl,1,2,3,4-tetrahydropyrimidin-2,4dione-yl (optionally substituted by C₁₋₄alkyl) or tetrahydrothienyl;or a pharmaceutically acceptable salt or solvate thereof, or a solvateof such a salt.

The compounds of formula (I) exist in isomeric forms and the presentinvention covers all such forms and mixtures thereof in all proportions.Both the pure enantiomers, racemic mixtures and equal and unequalmixtures of two enatiomers are within the scope of the presentinvention. It should also be understood that all the diastereomericforms possible are within the scope of the invention.

The term C₁₋₄ alkyl denotes a straight or branched alkyl group having 1to 4 carbon atoms in the chain. Examples of alkyl include methyl, ethyl,n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and tert-butyl.

The term C₁₋₄ alkoxy denotes an alkyl-O-group, where alkyl is straightor branched chain and examples include methoxy and ethoxy.

Halogen includes fluoro, chloro, bromo and iodo (but is, for example,fluoro or chloro).

An N-linked 5- or 6-membered heterocyclic ring is, for example, apyrrolidinyl, piperidinyl or piperazinyl ring.

In one particular aspect the present invention provides a compound offormula (I) wherein R¹ is phenyl {optionally substituted by halogen,hydroxy, cyano, C₁₋₄ alkyl (itself optionally mono-substituted by cyanoor hydroxy), C₁₋₄ alkoxy, CF₃, OCF₃, methylenedioxy, C(O)NH₂, S(O)₂NH₂or phenyl (itself optionally substituted by halogen)}, pyridinyl ortetrahydrothienyl; R² is aminopyridinyl, aminothiazolyl or3-azabicyclo[3.2.1]octyl; provided that when R² is 6-aminopyridin-3-ylthen R¹ is substituted phenyl, pyridinyl or tetrahydrothienyl; or apharmaceutically acceptable salt or solvate thereof, or a solvate ofsuch a salt.

In another aspect the invention provides a compound of formula (I)wherein R¹ is phenyl {optionally substituted (for example carrying 1 or2 substituents) by halogen, hydroxy, cyano, C₁₋₄ alkyl (itselfoptionally mono-substituted by cyano, hydroxy or phenyl), C₁₋₄ alkoxy,CF₃, OCF₃, methylenedioxy, phenoxy (itself optionally substituted byhalogen), tetrahydrofuranyloxy or tetrahydrofuranylmethoxy}, naphthyl,pyridinyl or tetrahydrothienyl.

In yet another aspect the present invention provides a compound offormula (I) wherein R¹ is phenyl {substituted (for examplemono-substituted) by halogen, hydroxy, cyano, C₁₋₄ alkyl (itselfoptionally mono-substituted by cyano or hydroxy), C₁₋₄ alkoxy (forexample methoxy), CF₃ or methylenedioxy} or tetrahydrothienyl.

In a still further aspect the present invention provides a compound offormula (I) wherein R¹ is phenyl {mono-substituted by halogen (forexample chloro or fluoro), hydroxy, cyano, C₁₋₄ alkyl (mono-substitutedby cyano), CF₃ or methylenedioxy} or tetrahydrothienyl.

Aminopyridinyl is, for example, 6-aminopyridin-3-yl. Aminothiazolyl is,for example, 2-aminothiazol-5-yl. 3-Azabicyclo[3.2.1]octyl is, forexample, 3-azabicyclo[3.2.1 ]oct-8-yl.

In a further aspect the present invention provides a compound of formula(I) wherein R² is aminopyridine (for example 6-aminopyridin-3-yl).

The compounds of the present invention can be prepared by adaptation ofmethods described in the literature (for example WO 00/66557), or byusing or adapting the methods of Examples 1, 26 or 51 below. It will beappreciated that when adapting methods of the literature or Examples 1,26 or 51 functional groups of intermediate compounds may need to beprotected by protecting groups. The preparations of certainintermediates are presented in Schemes 1 and 2.

For example a compound of formula (I) can be prepared by reacting acompound of formula (II):

wherein R¹ is as defined above or includes a group that can besubsequently reacted to form the group R¹, R* is a suitable protectinggroup (such as a C₁₋₆ alkyl group (for example tert-butyl)) and R² is asdefined above or the amine function of R² can be protected (for exampleby a tert-butoxycarbonyl group), with a thiol of formula L-SH, wherein Lis a suitable protecting group (for example 4-methoxybenzyl), in thepresence of a suitable catalyst (for example sodium hydride) and in asuitable solvent (for example N,N-dimethyl formamide) to form a compoundof formula (III):

and, optionally reacting the functional group on R¹ (for example R¹might include an acid group that can be coupled with an amino functionto form an amide in the presence of a catalyst (such as HATU)), andsubsequently removing the protecting groups as necessary.

Functional groups which it is desirable to protect include hydroxy,carboxylate and amino groups. Suitable protecting groups for hydroxyinclude trialkylsilyl or diarylalkyl-silyl (for exampletert-butyldimethylsilyl, tert-butyldiphenylsilyl or trimethylsilyl),tetrahydropyranyl, methoxymethyl, benzyloxymethyl and 4-methoxybenzyl.Suitable protecting groups for carboxylate include ethyl, tert-butyl andbenzyl esters. Suitable protecting groups for amino includetert-butyloxycarbonyl, 2,4,6-trimethoxybenzyl and benzyloxycarbonyl. Theuse of protecting groups is described in ‘Protective Groups in OrganicSynthesis’, third edition, T. W. Greene & P. G. M. Wutz,Wiley-Interscience (1999). The protective group may also be a polymerresin such as Wang resin or a 2-chorotrityl chloride resin.

The compounds of the invention are inhibitors of carboxypeptidase U andare thus expected to be useful in those conditions where inhibition ofcarboxypeptidase U is beneficial, such as in the treatment orprophylaxis of thrombosis and hypercoagulability in blood and tissues,atherosclerosis, adhesions, dermal scarring, cancer, fibroticconditions, inflammatory diseases and those conditions which benefitfrom maintaining or enhancing bradykinin levels in the body of mammals,such as man.

In a further aspect of the invention a compound of formula (I), or apharmaceutically acceptable salt or solvate thereof, or a solvate ofsuch a salt, is used in the in the treatment or prophylaxis ofthrombosis. In another aspect of the invention a compound of formula(I), or a pharmaceutically acceptable salt or solvate thereof, or asolvate of such a salt, is used in method of manufacturing a medicamentfor the treatment or prophylaxis of thrombosis.

It is known that hypercoagulability may lead to thrombo-embolicdiseases. Conditions associated with hypercoagulability andthrombo-embolic diseases which may be mentioned include protein Cresistance and inherited or aquired deficiences in antithrombin III,protein C, protein S and heparin cofactor II. Other conditions known tobe associated with hypercoagulability and thrombo-embolic diseaseinclude circulatory and septic shock, circulating antiphospholipidantibodies, hyperhomocysteinemia, heparin induced thrombocytopenia anddefects in fibrinolysis. The compounds of the invention are thusindicated both in the therapeutic and/or prophylactic treatment of theseconditions.

Other disease states which maybe mentioned include the therapeuticand/or prophylactic treatment of venous thrombosis and pulmonaryembolism, arterial thrombosis (for example in myocardial infarction,unstable angina, thrombosis-based stroke and peripheral arterialthrombosis) and systemic embolism usually from the atrium during atrialfibrillation or from the left ventricle after transmural myocardialinfarction.

The compounds of the invention are further indicated in the treatment ofconditions where there is an undesirable excess of proCPU/CPU.

Moreover, the compounds of the invention are expected to have utility inprophylaxis of re-occlusion and restenosis (that is, thrombosis) afterthrombolysis, percutaneous trans-luminal intervention (PTI) and coronarybypass operations; the prevention of re-thrombosis after microsurgeryand vascular surgery in general.

Further indications include the therapeutic and/or prophylactictreatment of disseminated intravascular coagulation caused by bacteria,multiple trauma, intoxication or any other mechanism, fibrinolytictreatment when blood is in contact with foreign surfaces in the body,such as vascular grafts, vascular stents, vascular catheters, mechanicaland biological prosthetic valves or any other medical device, andfibrinolytic treatment when blood is in contact with medical devicesoutside the body, such as during cardiovascular surgery using aheart-lung machine or in haemodialysis.

Furthermore, the compounds of the invention are expected to have utilityin prophylaxis of atherosclerotic progression and transplant rejectionin patients subject to organ transplantation, for example renaltransplantation.

The compounds of the invention are also expected to have utility ininhibiting tumor maturation and progression.

Moreover, the compounds of the invention are expected to have utility intreatment of any condition in which fibrosis is a contributing factor.Such fibrotic conditions include cystic fibrosis, pulmonary fibroticdisease eg chronic obstructive pulmonary disease (COPD), adultrespiratory distress syndrome (ARDS), fibromuscular dysplasia, fibroticlung disease and fibrin deposits in the eye during opthalmic surgery.

The compounds of the invention are also expected to have utility intreatment of inflammation. In particular the invention may be used forthe treatment or prevention of inflammatory diseases such as asthma,arthritis, endometriosis, inflammatory bowel diseases, psoriasis andatopic dermatitis.

The compounds of the invention are also expected to have utility intreatment of neurodegenerative diseases such as Alzheimers andParkinsons.

The compounds of the invention are also expected to have utility intreatment of conditions known to benefit from maintaining or enhancingbradykinin levels. Such conditions include hypertension, angina, heartfailure, pulmonary hypertension, renal failure and organ failure.

The compounds of the invention may also be combined and/orco-administered with any antithrombotic agent with a different mechanismof action, such as an anticoagulant (for example a vitamin K antagonist,an unfractionated or low molecular weight heparin, a synthetic heparinfragment such as fondaparinux, a thrombin inhibitor, a factor Xainhibitor or other coagulation factor/enzyme inhibitor, a recombinantcoagulation factor such as a recombinant human activated protein C) oran antiplatelet agent (such as acetylsalicylic acid, dipyridamole,ticlopidine, clopidogrel or other ADP-receptor [such as a P2Y12 or P2Y1]antagonist, a thromboxane receptor and/or synthetase inhibitor, afibrinogen receptor antagonist, a prostacyclin mimetic or aphosphodiesterase inhibitor). The compounds of the invention may furtherbe combined and/or coadministered with thrombolytics such as tissueplasminogen activator (natural, recombinant or modified), streptokinase,urokinase, prourokinase, anisoylated plasminogen-streptokinase activatorcomplex (APSAC), animal salivary gland plasminogen activators, and thelike, in the treatment of thrombotic diseases, in particular myocardialinfarction, ischaemic stroke and massive pulmonary embolism.

The compounds of the invention should have a selectivity forcarboxypeptidase U over carboxypeptidase N of >100:1, forexample >1000:1, using the assay described below.

The inhibiting effect of the compounds of the present invention wasestimated using the assay described in: Dirk Hendriks, Simon Scharpé andMarc van Sande, Clinical Chemistry, 31, 1936-1939 (1985); and Wei Wang,Dirk F. Hendriks, Simon S. Scharpé, The Journal of Biological Chemistry,269, 15937-15944 (1994).

Thus, the present invention provides a compound of formula (I), or apharmaceutically acceptable salt or solvate thereof, or a solvate ofsuch a salt, as hereinbefore defined for use in therapy.

In a further aspect, the present invention provides the use of acompound of formula (I), or a pharmaceutically acceptable salt orsolvate thereof, or a solvate of such a salt, as hereinbefore defined inthe manufacture of a medicament for use in therapy.

In the context of the present invention, the term “therapy” includes“prophylaxis” unless there are specific indications to the contrary. Theterms “therapeutic” and “therapeutically” should be understoodaccordingly.

The invention also provides a method of treating a condition whereinhibition of carboxypeptidase U is beneficial in a mammal sufferingfrom, or at risk of, said condition, which comprises administering tothe mammal a therapeutically effective amount of a compound of formula(I), or a pharmaceutically acceptable salt or solvate thereof, or asolvate of such a salt, as hereinbefore defined.

For the above-mentioned therapeutic uses the dosage administered willvary with the compound employed, the mode of administration, thetreatment desired and the disorder indicated.

The compounds of formula (I) and pharmaceutically acceptable salts,solvates or solvates of salts thereof may be used on their own but willgenerally be administered in the form of a pharmaceutical composition inwhich the formula (I) compound, salt, solvate or solvate of salt (activeingredient) is in association with a pharmaceutically acceptableadjuvant, diluent or carrier. Depending on the mode of administration,the pharmaceutical composition will, for example, comprise from 0.05 to99% w (percent by weight), such as from 0.05 to 80% w, for example from0.10 to 70% w, such as from 0.10 to 50% w, of active ingredient, allpercentages by weight being based on total composition.

The present invention thus also provides a pharmaceutical compositioncomprising a compound of formula (I), or a pharmaceutically acceptablesalt or solvate thereof, or a solvate of such a salt, as hereinbeforedefined, in association with a pharmaceutically acceptable adjuvant,diluent or carrier.

The invention further provides a process for the preparation of apharmaceutical composition of the invention which comprises mixing acompound of formula (I), or a pharmaceutically acceptable salt orsolvate thereof, or a solvate of such a salt, as hereinbefore defined,with a pharmaceutically acceptable adjuvant, diluent or carrier.

Also included in the invention are derivatives of compounds of formula(I) which have the biological function of compounds of formula (I), suchas prodrugs. Prodrugs are, for example, (pivaloyloxy)methyl esters and[(ethoxycarbonyl)oxy]methyl esters of carboxylic acids.

The following Examples illustrate the invention.

EXAMPLES

General Experimental Procedures

Mass spectra were recorded on a VG Platform II or a Micromass ZQ massspectrometer equipped with an electrospray interface (LC-MS). Highresolution mass spectra were recorded on a Micromass LCT massspectrometer equipped with an electrospray interface (LC-HRMS). ¹H NMRmeasurements were performed on Varian UNTIY plus 400, 500 and 600spectrometers, operating at ¹H frequencies of 400, 500 and 600 MHzrespectively. NMR spectra were recorded in DMSO, D₂O, CD₃CN or mixturesthereof. Chemical shifts are given in ppm with the solvent as internalstandard. Chromatography separations were performed using Merck Silicagel 60 (0.063-0.200 mm). The compounds named below were named usingACD/Name version 6.06/ 11 Jun. 2002 available from advanced chemistrydevelopment inc., Canada.

Example 1

This Example illustrates the preparation of2-[(6-aminopyridin-3-yl)methyl]-5-(1,1′-biphenyl-3-yl)-3-mercaptopentanoic acid

(a) 3-(1,1′-Biphenyl-3-yl)propanal

To a solution of 3-iodo-1,1′-biphenyl (0.964 g, 3.44 mmol) andtetrabutylammonium chloride (0.956 g, 3.44 mmol) in dry DMF (3 mL) wasadded alkyl alcohol (0.351 mL, 5.16 mmol), sodium hydrogencarbonate(0.723 g, 8.60 mmol), and palladium(II) acetate (31 mg, 0.14 mmol), andthe mixture was stirred at room temperature for 18 h. The reactionmixture was then diluted with EtOAc and the solid material filtered off(Celite). The filtrate was washed with water three times, dried (Na₂SO₄)and concentrated. Flash chromatography (heptan/tert-butyl methyl ether,4:1) of the residue gave 3-(1,1′-biphenyl-3-yl)propanal (0.601 g, 83%).

(b) tert-Butyl5-(1,1′-biphenyl-3-yl)-2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)pent-2-enoate

A solution of tert-butyl3-{6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}-2-(diethoxyphosphoryl)propanoate(1.058 g, 2.31 mmol) in dry THF (4 mL) was added to a solution of sodiumhydride (0.111 g, 60% in mineral oil, 2.77 mmol) in dry TBF (3 mL) at 0°C. and the mixture was stirred at 0° C. for 60 min. To this mixture asolution of 3-(1,1′-biphenyl-3-yl)propanal (0.582 g, 2.77 mmol) in dryTBF (3 mL) was added, and the reaction mixture was allowed to attainroom temperature over 22 h. EtOAc was then added, and the organic phasewas washed with saturated aqueous NH₄Cl and water, dried (Na₂SO₄) andconcentrated. Flash chromatography (toluene/EtOAc, 15:1) of the residuegave tert-butyl5-(1,1′-biphenyl-3-yl)-2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)pent-2-enoate(1.105 g, 93%) as a mixture of E/Z-isomers.

(c) tert-Butyl5-(1,1′-biphenyl-3-yl)-2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]pentanoate

A solution of 4-methoxy-α-toluenethiol (0.58 mL, 4.17 mmol) in dry,degassed DMF (2 mL) was treated at room temperature with a catalyticamount of sodium hydride (60% in mineral oil), followed by a solution oftert-butyl5-1,1′-biphenyl-3-yl)-2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)pent-2-enoate(1.073 g, 2.08 mmol) in dry, degassed DMF (5 mL). After 20 h at roomtemperature the reaction mixture was diluted with EtOAc and washed withwater three times. The organic layer was dried Na₂SO₄), concentrated,and subjected to flash chromatography (heptan/EtOAc, 3:1 andtoluene/EtOAc 12:1) to give tert-butyl5-(1,1′-biphenyl-3-yl)-2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]pentanoate(1.251 g, 90%)

(d)2-[(6-Aminopyridin-3-yl)methyl]-5-(1,1′-biphenyl-3-yl)-3-mercaptopentanoicacid

tert-Butyl5-(1,1′-biphenyl-3-yl)-2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4methoxybenzyl)thio]pentanoate(0.669 g, 1.00 mmol) was dissolved in triethylsilane (0.75 mL) andtrifluoroacetic acid (6.0 mL). The solution was heated to 60° C. for 3 hand then concentrated. Purification of the residue by reversed-phaseHPLC (C-8 column, linear gradient 40%→100% of MeCN in 5% aqueous MeCNcontaining 0.15% trifluoroacetic acid) gave the title diastereomericcompound as the trifluoroacetic salt (0.342 g, 68%) after freeze-drying.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.70 (dd,J=2.1, 9.2 Hz, 0.5 H), 7.66(dd,J=2.1, 9.2 Hz, 0.5 Hz), 7.61-7.58 (m, 2 H), 7.53-7.51 (m, 1 H),7.46-7.41 (m, 4 H), 7.38-7.32 (m, 2 H), 7.22-7.16 (m, 1 H), 6.88(d,J=9.1 Hz, 0.5 H), 6.84 (d,J=9.1 Hz, 0.5 H), 3.10-2.74 (m, 6 H),2.17-2.04 (m, 1 H), 1.91-1.78 (m, 1 H). ¹³C NMR (101 MHz, CD₃CN/D₂O): δ175.3, 174.9, 153.0, 146.0, 145.8, 142.3, 141.1, 140.9, 134.0, 133.9,129.4, 129.2, 127.9, 127.9, 127.8, 127.3, 127.2, 127.1, 124.9, 124.8,124.4, 124.1, 113.9, 113.8, 53.6, 53.0, 41.3, 40.5, 37.9, 33.1, 33.0,31.2, 30.3. HRMS (ESI) calculated for C₂₃H₂₅N₂O₂S 393.1637 (M+H)=hu +,found 393.1650.

Example 2

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-(1-naphthyl)pentanoic acidwas synthesised according to the procedure for Example 1.

¹H NMR (400 MHz, CDCl₃): δ 8.14-8.10 (d, 1 H), 7.93-7.89 (d, 1 H),7.80-7.54 (m, 1 H), 7.67-7.35 (m, 6 H), 6.83-6.77 (m, 1 H), 3.52-3.35(m,1 H), 3.22-3.12 (m, 2 H), 2.90-2.80 (m, 3 H), 2.25-2.13 (m, 1 H),2.05-1.87 (m, 1 H). HRMS (ESI) calculated for C₂₁H₂₃N₂O₂S 367.1480(M+H)⁺, found 367.1497.

Example 3

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-cyanophenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.73 (dd,J=2.2, 9.3 Hz, 0.5 H), 7.70(dd,J=2.2, 9.3 Hz, 0.5 H), 7.58-7.40 (m, 5 H), 6.90 (d,J=9.1 Hz, 0.5 H),6.88 (d,J=9.3 Hz, 0.5 H), 2.99-2.88 (m, 2 H), 2.82-2.71 (m, 4 H),2.12-2.00 (m, 1 H), 1.88-1.74 (m, 1 H).

¹³C NMR (101 MHz, CD₃CN/D₂O): δ 175.5, 174.9, 153.0, 146.0, 145.8,143.1, 133.9, 132.4, 132.3, 130.3, 130.3, 129.8, 124.3, 124.0, 119.4,113.9, 113.9, 111.6, 53.8, 52.8, 41.1, 40.2, 37.4, 32.5, 32.5, 31.1,30.5. HRMS (ESI) calcd for C₁₈H₂₀N₃O₂S 342.1276 (M+H)⁺, found 342.1277

Example 4

5-[3-(Aminocarbonyl)phenyl]-2-[(6-aminopyridin-3-yl)methyl]-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1, startingfrom 3-iodo-N-(2,4,6-trimethoxybenzyl)benzamide.3-iodo-N-(2,4,6-trimethoxybenzyl)benzamide was synthesised from3-iodobenzoic acid using standard procedures.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.72-7.67 (m, 1 H), 7.65-7.61 (m, 2 H),7.52-7.49 (m,1 H), 7.42-7.35 (m, 2 H), 6.89 (d,J=9.3 Hz, 0.7 H), 6.85(d,J=9.1 Hz, 0.3 H), 3.00-2.87 (m, 2 H), 2.81-2.72 (m, 4 H), 2.13-2.00(m, 1 H), 1.90-1.86 (m, 1 H).

¹³C NMR (101 MHz, CD₃CN/D₂O): δ 175.7, 175.1, 171.5, 161.7, 161.4,153.0, 146.0, 145.8, 142.1, 142.0, 133.9, 133.4, 132.7, 129.1, 127.8,127.7, 125.5, 124.3, 124.0, 114.0, 113.9, 53.7, 52.6, 41.0, 39.9, 37.7,37.6, 32.8, 32.7, 31.0, 30.4. HRMS (ESI) calcd for C₁₈H₂₂N₃O₃S 360.1382(M+H)⁺, found 360.1378.

Example 5

2-[(6-Aminopyridin-3-yl)methyl]-5-[2-fluoro4-(trifluoromethyl)phenyl]-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.75-7.71 (m, 1 H), 7.56 (d,J=1.6 H, 1H), 7.47-7.35 (m, 3 H), 6.91 (d,J=9.3 Hz, 1 H),3.04-2.91 (m, 1 H),2.88-2.74 (m, 4 H).

¹³C NMR (101 MHz, CD₃CN/D₂O): δ 175.4, 174.9, 162.0, 161.4, 159.6,153.0, 146.0, 145.9, 134.0, 133.2, 133.0, 129.9, 124.2, 124.0, 121.4,114.0, 113.9, 112.8, 112.6, 53.8, 53.0, 41.5, 40.8, 36.3, 36.2, 31.2,30.6, 26.5. HRMS (ESI) calcd for C₁₈H₁₉F₄N₂O₂S 403.1103 (M+H)⁺, found403.1137.

Example 6

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-chlorophenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (500 MHz, CD₃CN/D₂O): δ 7.75 (dd, 0.5 H), 7.72 (dd, 0.5 H), 7.56(d, 0.5 H), 7.54 (d, 0.5 H), 7.30-7.10 (m, 4 H), 6.92 (d, 0.5 H), 6.91(d, 0.5 H), 3.02-2.65 (m, 6 H), 2.10-2.00 (m, 1 H), 1.88-1.74 (m, 1 H).MS (ESI) 351.1 (M+H)⁺.

Example 7

2-[(6-Aminopyridin-3-yl)methyl]-5-(1,3-benzodioxol-5-yl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.72(dd, 1 H), 7.69 (d, 0.5 H), 7.55 (s,0.5 H), 7.53 (s, 0.5 H), 6.89 (m, 1 H), 6.77-6.60 (m, 3 H), 5.88(s, 2H), 3.0-2.70 (m, 5 H), 2.58-2.68 (m, 1 H), 1.92-2.08 (m, 1 H),1.69-1.81(m, 1 H). HRMS (ESI) calculated for C₁₈H₂₀N₂O₄S 361.1222(M+H)⁺, found 361.1236.

Example 8

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-pyridin-2-ylpentanoic acidwas synthesised according to the procedure for Example 1, starting from3-pyridin-2-ylpropanal.

¹H NMR (600 MHz, D₂O) δ ppm 1.90-2.37 (m, 2 H), 2.70-2.98 (m, 3 H),3.05-3.11 (m, 1 H), 3.12-3.24 (m, 1 H), 3.32-3.41 (m, 1 H), 6.89 (d, 1H), 7.57 (s, 1 H), 7.75 (dd, 1 H), 7.80-7.85 (m, 1 H), 7.88 (d, 1 H),8.39-8.46 (m, 1 H), 8.54-8.60 (m, 1 H). MS (ESI) 318.2 (M+H)⁺.

Example 9

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-(3,4,5-triethoxyphenyl)pentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (600 MHz, CD₃CN/D₂O) δ ppm 1.71-1.87 (m, 1 H), 1.98-2.10 (m, 1H), 2.58-2.70 (m, 1 H), 2.73-2.87 (m, 4 H), 2.90 (d, 0.5 H), 2.88-3.02(m, 0.5 H), 3.65 (s, 3 H), 3.75 (s, 3 H), 3.75 (s, 3 H), 6.48 (s, 1 H),6.49 (s, 1 H), 6.88 (d, 0.5 H), 6.89 (d, 0.5 H), 7.52 (d, 1 H),7.67-7.72 (m, 1 H). MS (ESI) 407.2 (M+H)⁺.

Example 10

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-pyridin-3-ylpentanoic acidwas synthesised according to the procedure for Example 1, starting from3-pyridin-3-ylpropanal.

¹H NMR (600 MHz, CD₃CN/D₂O) δ ppm 1.78-1.90 (m, 1 H), 2.03-2.19 (m, 1H), 2.71-2.78 (m, 1 H), 2.78-3.02 (m, 4 H), 3.07-3.18 (m, 1 H), 6.90 (d,1 H), 7.56 (s, 1 H), 7.73-7.76 (m, 1 H), 7.91-7.95 (m, 1 H), 8.40-8.44(m, 1 H), 8.55-8.59 (m, 2 H). MS (ESI) 318.2 (M+H)⁺.

Example 11

2-[(6-Aminopyridin-3-yl)methyl]-5-[4-(cyanomethyl)phenyl]-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (500 MHz, CD₃CN/D₂O): δ 7.99(dd, 0.5 H), 7.96 (dd, 0.5 H), 7.81(d, 0.5 H), 7.80 (d, 0.5 H), 7.56-7.46 (m, 4 H), 7.17 (d, 0.5 H), 7.15(d, 0.5 H), 4.11 (s, 2 H), 3.26-2.97 (m, 6 H), 2.40-2.25 (m, 1 H),2.17-2.02 (m, 1 H). MS (ESI) 356.2 (M+H)⁺.

Example 12

2-[(6-Aminopyridin-3-yl)methyl]-5-(2-hydroxyphenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1, startingfrom 1-iodo-2-[(4-methoxybenzyl)oxy]benzene.1-iodo-2-[(4-methoxybenzyl)oxy]benzene was synthesised from 2-iodophenolusing standard procedures.

¹H NMR (500 MHz, 90% CD₃CN/D₂O) δ ppm 1.72-1.87 (m, 1 H), 2.00-2.15 (m,1 H), 2.60-2.75 (m, 1 H), 2.77-2.94 (m, 4.6 H), 3.06-3.11 (m, 0.4 H),6.75-6.81 (m, 2 H), 6.90-6.94 (m, 1 H), 7.02-7.13 (m, 2 H), 7.56 (d,0.6H), 7.57 (d, 0.4 H), 7.75 (dd, 0.6 H), 7.77 (dd, 0.4 H). MS (ESI) 333.2(M+H)⁺.

Example 13

2-[(6-Aminopyridin-3-yl)methyl]-5-[4-(aminosulfonyl)phenyl]-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1, startingfrom 4-iodo-N-(2,4,6-trimethoxybenzyl)benzenesulfonamide.4-iodo-N-(2,4,6-trimethoxybenzyl)benzenesulfonamide was synthesised from4-iodobenzenesulfonyl chloride using standard procedures.

¹H NMR (500 MHz, 75% CD₃CN/D₂O) δ ppm 1.79-1.92 (m, 1 H), 2.04-2.18 (m,1 H), 2.76-2.88 (m, 4 H), 2.90-3.07 (m, 2 H), 6.92 (d, 0.5 H), 6.93 (d,0.5 H), 7.40 (d, 1 H), 7.42 (d, 1 H), 7.57 (d, 0.5 H), 7.58 (d, 0.5 H),7.72-7.81 (m, 3 H). MS (ESP) 396.1 (M+H)⁺.

Example 14

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-(4-methoxyphenyl)pentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (500 MHz, 75% CD₃CN/D₂O) δ ppm 1.73-1.85 (m, 1 H), 1.99-2.11 (m,1 H), 2.61-2.72 (m, 1 H), 2.75-2.95 (m, 4.5 H), 2.98-3.04 (m, 0.5 H),3.75 (s, 1.5 H), 3.76 (s, 1.5 H), 6.82-6.88 (m, 2 H), 6.92 (d, 0.5 H),6.93 (d, 0.5 H), 7.12 (d, 0.5 H), 7.15 (d, 0.5 H), 7.56 (s, 0.5 H), 7.58(s, 0.5 ), 7.72-7.78 (m, 1 H). MS (ESI) 347.2 (M+H)⁺.

Example 15

2-[(6-Aminopyridin-3-yl)methyl]-5-(4-hydroxyphenyl)-3-mercaptopentanoicacid was synthesized from2-[(6-aminopyridin-3-yl)methyl]-3-mercapto-5-(4-methoxyphenyl)pentanoicacid using standard conditions for the methoxy group hydrolysis(concentrated aqueous hydrochloric acid at reflux under argon for 24 h).

1H NMR (500 MHz, 25% CD₃CN in D₂O) δ ppm 1.73-1.85 (m, 1 H), 1.94-2.09(m, 1 H), 2.59-2.68 (m, 1 H), 2.75-2.87 (m, 4 H), 2.90 (d, 0.5 H),2.98-3.03 (m, 0.5 H), 6.71-6.76 (m, 2 H), 6.90-6.95 (m, 1 H), 7.00-7.07(m, 2 H), 7.54-7.57 (m, 1 H), 7.71-7.76 (m, 1 H). MS (ESI) 333.2 (M+H)⁺.

Example 16

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-[4-(trifluoromethoxy)phenyl]-pentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (500 MHz, CD₃CN/D₂O) δ ppm 1.76-1.88 (m, 1 H), 2.01-2.14 (m, 1II), 2.66-3.07 (m, 6 H), 6.94 (d, 1 H), 7.16-7.25 (m, 2 H), 7.26-7.34(m, 2 H), 7.59 (d, 1 H), 7.78 (dd, 1 H). MS (ESI) 401.3 (M+H)⁺.

Example 17

2-[(6-Aminopyridin-3-yl)methyl]-5-(1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (500 MHz, CD₃CN/D₂O) δ ppm 1.57-1.76 (m, 1 H), 1.92-2.06 (m, 1H), 2.31-2.45 (m, 1 H), 2.53-2.63 (m, 1 H), 2.75-3.07 (m, 4 H), 3.22 (s,1.5 H), 3.23 (s, 1.5 H) 3.30 (s, 1.5 H), 3.30 (s, 1.5 H), 6.94 (d, 1 H),7.30 (s, 0.5 H), 7.32 (s, 0.5 H), 7.59-7.64 (m, 1 H), 7.80 (dd, 1 H). MS(ESI) 379.2 (M+H)⁺.

Example 18

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-(tetrahydro-2-thienyl)pentanoicacid was synthesised according to the procedure for Example 1, startingfrom 3-thien-2-ylpropanal.

¹H NMR (500 MHz, 90% CD₃CN/D₂O) δ ppm 1.48-1.60 (m, 3 H), 1.70-1.90 (m,3 H), 2.00-2.10 (m,2 H), 2.70-3.10 (m, 6 H), 3.25-3.33 (m, 1 H), 6.92(d, 1 H), 7.59 (s, 1 H), 7.78 (dd, 1 H). MS (ESI) 327.3 (M+H)⁺.

Example 19

2-[(6-Aminopyridin-3-yl)methyl]-5-[3-(hydroxymethyl)phenyl]-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1, startingfrom 1-iodo-3-{[(4-methoxybenzyl)oxy]methyl}benzene.1-iodo-3-{[(4-methoxybenzyl)oxy]methyl}benzene was synthesized from(3-iodophenyl)methanol using standard procedures.

¹H NMR (500 MHz, CD₃CN/D₂O) δ ppm 1.94-2.10 (m, 1 H), 2.21-2.37 (m, 1H), 2.78-3.24 (m, 6 H), 4.77 (s, 1 H), 4.78 (s, 1 H), 7.09 (d, 0.5 H),7.12 (d, 0.5 H), 7.34-7.44 (m, 3 H), 7.48-7.54 (m, 1 H), 7.73 (d, 0.5H),7.74 (d, 0.5 H), 7.91 (dd, 0.5H), 7.96 (dd, 0.5 H). MS (ESI) 347.3(M+H)⁺.

Example 20

2-[(6-Aminopyridin-3-yl)methyl]-5-[2-(2,4-dichlorophenoxy)phenyl]-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (400 MHz, CDCl₃): δ 7.64 (d, 1 H), 7.51 (d, 1 H), 7.40 (d, 1 H),7.27 (m, 1 H), 7.18-7.04 (m, 3 H), 7.78-7.69 (m, 3 H), 3.15-2.92(m, 2H), 2.87-2.65 (m, 4 H) ,2.21-2.08 (m, 1 H), 1.89-1.75 (m, 1 H). HRMS(ESI) calculated for C₂₃H₂₂Cl₂N₂O₃S 477.0806 (M+H)⁺, found 477.0170.

Example 21

2-[(6-Aminopyridin-3-yl)methyl]-5-(3,5dimethylphenyl)3-mercaptopentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (500 MHz, CD₃CN/D₂O) δ ppm 1.72-1.85 (m, 1 H), 1.97-2.11(m, 1 H),2.23 (s, 3 H), 2.24 (s, 3 H), 2.57-2.66 (m, 1 H), 2.75-2.87 (m, 4 H),2.90 (d, 0.5 H), 2.99-3.05 (m, 0.5 H), 6.78-6.85 (m, 3 H), 6.88-6.94 (m,1 H), 7.54 (d, 0.5 H), 7.56 (d, 0.5 H), 7.71 (dd, 0.5 H), 7.73 (d, 0.5H). MS (ESI) 345.2 (M+H)⁺.

Example 22

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-(4propylphenyl)pentanoicacid was synthesised according to the procedure for Example 1.

¹H NMR (500 MHz, CD₃CN/D₂O) δ ppm 0.84 (t, 3 H), 1.49-1.58 (m, 2 H),1.70-1.81 (m, 1 H), 1.96-2.04 (m, 1 H), 2.50 (t, 2 H), 2.60-2.70 (m, 1H), 2.71-2.93 (m, 4 H), 2.93-3.01 (m, 1 H), 6.88 (d, 1 H), 7.07-7.10 (m,4 H), 7.54 (d, 1 H), 7.71 (dd, 1 H). MS (ESI) 359.2 (M+H)⁺.

Example 23

2-[(6-Aminopyridin-3-yl)methyl]-5-4-benzylphenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1 startingfrom (4-iodophenyl)(phenyl)methanone.

¹H NMR (500 MHz, 80% CD₃CN/D₂O) δ ppm 1.72-1.82 (m, 1 H), 2.00-2.10 (m,1 H), 2.72-2.62 (m, 1 H), 2.78-3.04 (m, 5 H), 3.9 (s, 2 H), 6.90 (d, H),7.08-7.29 (m, 9 H), 7.55 (d, 1 H), 7.73 (dd, 1 H). HRMS (ESI) calculatedfor C₂₄H₂₇N₂O₂S 407.1793 (M+H)⁺, found 407.1804.

Example 24

2-[(2-Amino-1,3-thiazol-5-yl)methyl]-3-mercapto-5-phenylpentanoic acidwas synthesised according to the procedure for Example 1 starting fromtert-butyl3-{2-[(tert-butoxycarbonyl)amino]-1,3-thiazol-5-yl}-2-(diethoxyphosphoryl)propanoate.Tert-butyl3-{2-[(tert-butoxycarbonyl)amino]-1,3-thiazol-5-yl}-2-(diethoxyphosphoryl)propanoatewas synthesised as shown in Scheme 1.

¹H NMR (500 MHz, 90% CD₃CN/D₂O) δ ppm 1.78-1.90 (m, 1 H), 2.00-2.11 (m,1 H), 2.68-2.77 (m, 1 H), 2.78-3.2 (m, 4.5 H), 3.05-3.11 (m, 0.5 H),6.85-6.88 (m, 1 H), 7.16-7.33 (m, 5 H). MS (ESI) 323.2 (M+H)⁺.

Example 25

2-(3-Azabicyclo[3.2. 1]oct-8-ylmethyl)-3-mercapto-5-phenylpentanoic acidwas synthesised according to the procedure for Example 1 starting fromtert-butyl8-[3-tert-butoxy-2-(diethoxyphosphoryl)-3-oxopropyl]-3-azabicyclo[3.2.1]octane-3-carboxylate.Tert-butyl8-[3-tert-butoxy-2-(diethoxyphosphoryl)-3-oxopropyl]-3-azabicyclo[3.2.1]octane-3-carboxylatewas synthesised as shown in Scheme 2.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.90-7.80 (m, 2 H), 7.80-7.70 (m, 3 H),3.80-3.60 (m, 2 H), 3.60-3.35 (m, 4 H), 3.35-3.18 (m, 1 H), 3.18-3.00(m, 1 H), 2.90-1.80 (m, 11 H). MS (ESI) 333.5 (M+H)⁺.

Example 26

This Example illustrates the preparation of2-[(6-aminopyridin-3-yl)methyl]-3-mercapto-5-(3-{[methyl(2-phenylethyl)amino]carbonyl}phenyl)pentanoicacid.

(a) 3-{5-tert-butoxy4{6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio-5-oxopentyl}benzoicacid

KOH (5 mL of a IM solution in ethanol) was added to a solution of ethyl3-{5-tert-butoxy-4-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-oxopentyl}benzoate(0.27 g, 0.406 mmol, synthesised according to the procedure forExample 1) in ethanol (2 mL), and the mixture was stirred at roomtemperature for 2 h and then at 50° C. for 2 h. The reaction mixture wasthen diluted with diethyl ether and water. The organic phase wasextracted with 0.1M aqueous KOH and the combined aqueous phase wasacidified (pH 5) using 3M aqueous HCL. The aqueous phase was thenextracted with diethyl ether and the organic phase was washed withbrine, dried and concentrated. Purification of the residue byreversed-phase HPLC (C-8 column, linear gradient 40%→100% of MeCN in 5%aqueous MeCN containing 0.1 M ammonium acetate) gave a residue that wasdissolved in toluene and water and concentrated to give3-{5-tert-butoxy-4-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-oxopentyl}benzoicacid (0.12 g, 54%).

(b) tert-butyl 2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-(3-{[methyl(2-phenylethyl)amino]carbonyl}phenyl)pentanoate

N-methylphenethylamine (20 μL, 0.14 mmoL), HATU (55 mg, 0.15 mmoL) andiPr₂EtN (46 μL, 0.26 mmoL) was added to a solution of3-{5-tert-butoxy-4-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-oxopentyl}benzoicacid (84 mg, 0.132 mmol) in DMF (2 mL) under argon at 0° C. The reactionmixture was stirred for 2 h and was then quenched with ice. Diethyletherand water was added and the aqueous phase was extracted diethyl ether.The combined organic phase was dried and concentrated. Flashchromatography (heptan/EtOAc, 3:1) gave tert-butyl2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-(3-{[methyl(2-phenylethyl)amino]carbonyl}phenyl)pentanoate(81 mg, 81.4%).

(c)2-[(6-aminopyridin-3-yl)methyl]-3-mercapto-5-(3{[methyl(2-phenylethyl)amino]carbonyl}phenyl)pentanoic acid

tert-butyl2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-(3-{[methyl(2-phenylethyl)amino]carbonyl}phenyl)pentanoate (80mg, 0.106 mmol) was dissolved in triethylsilane (0.4 mL) andtrifluoroacetic acid (3.0 mL). The solution was heated to 60° C. for 1 hand was then concentrated. Purification of the residue by reversed-phaseHPLC (C-8 column, linear gradient 20%→100% of MeCN in 5% aqueous MeCNcontaining 0.15% trifluoroacetic acid) gave the title diastereomericcompound as the trifluoroacetic salt (64 mg, 100%) after freeze-drying.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.76-6.63 (m, 12 H), 3.71 (m, 1 H), 3.40(m, 1 H), 3.21-2.54 (m, 11 H), 2.12-1.63 (m, 2 H). HRMS (ESI) calcd forC₂₇H₃₁N₃O₃S 478.2164 (M+H)⁺, found 478.2133.

Example 27

3-[5-(6-Aminopyridin-3-yl)-4-carboxy-3-mercaptopentyl]benzoic acid wassynthesised according to the procedure for Example 26 starting from3-{5-tert-butoxy-4-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-oxopentyl}benzoicacid.

¹H NMR (400 MHz, D₂O): δ 8.05-8.01 (dd, 1 H), 8.01-7.99 (s,1 H),7.90-7.86 (dd, 1 H), 7.73-7.70 (s, 1 H), 7.68-7.58 (m, 2 H), 7.08-7.04(d, 1 H), 3.18-3.08 (m, 1 H), 3.06-2.90 (m, 5 H), 2.36-2.26 (m, 1 H),2.14-2.04 (m, 1 H). HRMS (ESI) calculated for C₁₈H₂₀N₂O₄S 361.1222(M+H)⁺, found 361.1212.

Example 28

2-[(6-Aminopyridin-3-yl)methyl]-5-[3-(3,4-dihydroisoquinolin-2(1H)-ylcarbonyl)phenyl]-3-mercaptopentanoic acid was synthesised according to theprocedure for Example 26.

¹H NMR (500 MHz, CD₃CN/D₂O): δ 7.73 (m, 1 H), 7.52 (s, 1 H), 7.44-7.11(m, 8 H), 6.90 (m, 1 H), 4.81 (s, 1 H), 4.54 (s, 1 H), 3.89 (br, 1 H),3.57 (br, 1 H), 2.99-2.65 (m, 8 H), 2.09 (m, 1 H), 1.85 (m, 1 H). HRMS(ESI) calcd for C₂₇H₂₉N₃O₃S 476.2008 (M+H)⁺, found 476.2002.

Example 29

2-[(6-Aminopyridin-3-yl)methyl]-5-{3-[(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)carbonyl]phenyl}-3-mercaptopentanoicacid was synthesised according to the procedure for Example 26.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.68 (m, 1 H), 7.49 (s, 1 H), 7.38-7.22(m, 4 H), 6.90-6.72 (m, 2.5 H), 6.47 (s, 0.5 H), 4.69 (s, 1 H), 4.44 (s,1 H), 3.96-3.46 (m, 8 H), 3.01-2.59 (m, 8 H), 2.17-1.67 (m, 2 H). HRMS(ESI) calcd for C₂₉H₃₃N₃O₅S 536.2219 (M+H)⁺, found 536.2248.

Example 30

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-{3-[(2-pyridin-2-ylethoxy)carbonyl]phenyl}pentanoic acid was synthesised according to theprocedure for Example 26.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 8.64 (d, 1 H), 8.46 (dd, 1 H), 7.98 (d, 1H), 7.88 (dd, 1 H), 7.77-7.64 (m, 3 H), 7.58-7.31 (m, 3 H), 6.89 (dd, 1H), 4.65 (t, 2 H), 3.50 (t, 2 H), 2.99-2.62 (m, 6 H), 2.03 (m, 1 H),1.79 (m, 1 H). HRMS (ESI) calcd for C₂₅H₂₇N₃O₄S 466.1803 (M+H)⁺, found466.1813.

Example 31

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[2-(2,6-dichlorophenyl)ethoxy]carbonyl}phenyl)-3-mercaptopentanoic acid was synthesisedaccording to the procedure for Example 26.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 7.69 (m, 3 H), 7.51 (s, 1 H), 7.38-7.28(m, 4 H), 7.12 (m, 1 H), 6.84 (m, 1 H), 4.48 (m, 2 H), 3.62 (m, 0.5 H1),3.31 (m, 2 H), 3.10 (m, 0.5 H), 2.98-2.53 (m, 5 H), 2.0 (m, 1 H), 1.75(m, 1 H). HRMS (ESI) calcd for C₂₆H₂₆Cl₂N₂O₄S 533.1069 (M+H)⁺, found533.1071.

Example 32

2-[(6-Aminopyridin-3-yl)methyl]-5-[3-(ethoxycarbonyl)phenyl]-3-mercaptopentanoicacid was synthesised according to the procedure for Example 26 startingfrom ethyl3-{5-tert-butoxy-4-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-oxopentyl}benzoate.

¹H NMR (500 MHz, CD₃CN/D₂O): δ 7.90(d, 1 H), 7.87 (s, 1 H), 7.74 (d, 1H), 7.58 (s, 1 H), 7.53 (d, 1 H), 7.48 (t, 1 H), 6.91 (d, 1 H), 4.41 (q,2 H), 2.95-3.03 (m, 1 H), 2.95-2.82 (m, 4 H), 2.75-2.80 (n, 1 H),2.14-2.23 (m, 1 H), 1.95-2.03 (m, 1 H), 1.41 (t, 3 H). HRMS (ESI)calculated for C₂₀H₂₅N₂O₄S 389.1535 (M+H)⁺, found 389.1555.

Example 33

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[(2-fluoroethyl)amino]carbonyl}phenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 26.

¹H NMR (500 MHz, 10% CD₃CN in D₂O): δ 7.95 (dd, 0.5 H), 7.90 (dd, 0.5H), 7.86-7.81 (m, 2 H), 7.75 (dd, 0.5 H), 7.73 (dd, 0.5 H), 7.70-7.60(m, 2 H), 7.13 (d, 0.5 H), 7.07 (d, 0.5 H), 4.89-4.86 (m, 1 H), 4.8-4.76(m, 1 H), 3.91-3.94 (m, 1 H, 3.85-3.89 (m, 1 H), 3.25-3.12 (m, 2.5 H),3.11-2.98 (m, 3 H), 2.92-2.97 (m, 0.5 H), 2.41-2.24 (m, 1 K), 2.21-2.01(m, 1 H). HRMS (ESI) calculated for C₂₀H₂₅FN₃O₃S 406.1600 (M+H)⁺, found406.1560.

Example 34

2-[(6-Aminopyridin-3-yl)methyl]-5-{3-[(dimethylamino)carbonyl]phenyl}-3-mercaptopentanoicacid was synthesised according to the procedure for Example 26.

¹H NMR (500 Mz, 5% CD₃CN/D₂O): δ 7.77(dd, 0.5 H), 7.72 (dd, 0.5 H),7.52-7.54 (m, 1 H), 7.45-7.32 (m, 2 H), 7.25-7.29 (m, 2 H), 6.91 (d, 0.5H), 6.93 (d, 0.5 H), 3.07 (s, 3 H), 2.95 (two s, 3 H), 3.05-2.71 (m, 6H), 2.19-2.0 (m, 1 H), 1.99-1.82 (m, 1 H). HRMS (ESI) calculated forC₂₀H₂₆N₃O₃S 388.1695 (M+H)⁺, found 388.1683.

Example 35

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-{3-[(vinylamino)carbonyl]phenyl}pentanoicacid was synthesised according to the procedure for Example 26.

¹H NMR (500 Mz, 10% CD₃CN/D₂O): δ 7.71(two dd, 1 H), 7.53 (two dd, 0.5H), 6.89 (m, 1 H), 6.77-6.60 (m, 3 H), 5.88(s, 2 H), 3.0-2.70 (m, 5 H),2.62 (m, 1 H), 2.00 (m, 1 H), 1.75(m, 1 H). HRMS (ESI) calculated forC₂₀H₂₄N₃O₃S 386.1538 (M+H)⁺, found 386.1470.

Example 36

2-[(6-Aminopyridin-3-yl)methyl]-5-[3-({[2-(1,3-benzodioxol-5-yl)ethyl]amino}carbonyl)phenyl]-3-mercaptopentanoic acid was synthesisedaccording to the procedure for Example 26.

¹H NMR (500 MHz, 20% CD₃CN/D₂O) δ ppm 1.88-2.06 (m, 1 H), 2.10-2.27 (m,1 H), 2.79-3.11 (m, 8 H), 3.68 (t, 2 H), 6.00 (s, 2 H), 6.85 (m, 1 H),6.90 (m, 2 H), 6.96 (d, 0.7 H), 7.01 (d, 0.3 H), 7.47 (m, 1.2 H), 7.51(m, 0.6 H), 7.56 (s, 0.7 H), 7.58 (s, 0.3 H), 7.62 (s, 2 H), 7.76 (d,0.7 H), 7.81 (d, 0.3 H). HRMS (ESI) calculated for C₂₇H₂₉N₃O₅S 508.1906(M+H)⁺, found 508.1935.

Example 37

2-[(6-Aminopyridin-3-yl)methyl]-5-{3-[(dibenzylamino)carbonyl]phenyl}-3-mercaptopentanoicacid was synthesised according to the procedure for Example 26.

¹H NMR (500 MHz, 50% CD₃CN/D₂O) δ ppm 2.28-2.40 (m, 1 H), 2.52-2.63 (m,1 H), 3.25-3.53 (m, 6 H), 4.99 (s, 2 H), 5.23 (s, 2 H), 7.46 (d, 0.4 H),7.48 (d, 0.6 H), 7.71 (d, 2 H), 7.83-8.00 (m, 12 H), 8.08 (s, 1 H), 8.25(dd, 0.4 H), 8.28 (dd, 0.6 H). HRMS (ESI) calculated for C₃₂H₃₃N₃O₃S540.2321 (M+H)⁺, found 540.2340.

Example 38

2-[(6-Aminopyridin-3-yl)methyl]-5-3-{[(2-hydroxyethyl)(methyl)amino]carbonyl}phenyl)-3-mercaptopentanoic acid was synthesisedaccording to the procedure for Example 26.

¹H NMR (500 MHz, 50% CD₃CN/D₂O) δ ppm 1.71-2.11 (m, 2 H), 2.67-2.96 (m,6 H), 2.89 (s, 1.5 H), 3.01 (s, 1.5 H), 3.34 (q, 1 H), 3.52-3.57 (m, 1H), 3.59 (t, 1 H), 3.77 (t, 1 H), 6.74-6.86 (m, 1 H), 7.12-7.41 (m, 4H), 7.45 (s, 1 H) 7.58-7.63 (m, 0.5 H), 7.65-7.69 (m, 0.5 H). HRMS (ESI)calculated for C₂₁H₂₈N₃O₄S 418.1800 (M+H)⁺, found 418.1752.

Example 39

2-[(6-Aminopyridin-3-yl)methyl]-5-{3-[(3-hydroxypyrrolidin-1-yl)carbonyl]phenyl}-3-mercaptopentanoic acid was synthesised according tothe procedure for Example 26.

¹H NMR (400 MHz, CD₃CN/D₂O): δ 8.35-8.15 (m, 1 H), 8.05 (br s, 1 H),8.00-7.75 (m, 4 H), 7.50-7.35 (m, 1 H), 6.16 (br m, 0.5 H), 6.02 (br m,0.5 H), 5.02 (br m, 0.5 H), 4.88 (br m, 0.5 H), 4.50-3.60 (m, 4 H),3.55-3.20 (m, 7 H), 3.0-2.2 (m, 4 H). HRMS (ESI) calculated forC₂₂H₂₈N₃O₄S 430.1829 (M+H)⁺, found 430.1801.

Example 40

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[4-(4-chlorophenyl)piperazin-1-yl]carbonyl}phenyl)-3-mercaptopentanoic acid was synthesised accordingto the procedure for Example 26.

¹H NMR (400 MHz, CD₃CN): δ 7.75-7.67 (m, 1 H), 7.52-7.47 (dd, 1 H),7.40-7.28(m, 5 H), 7.12-7.07 (m, 3 H), 6.90-6.84 (m, 1 H), 4.00-3.50 (m,4 H), 3.40-3.20 (m, 4 H), 3.03 -2.90 (m, 1 H), 2.87-2.70 (m, 5 H),2.17-2.03 (m, 1 H) ,1.97-1.89 (m, 1 H). HRMS (ESI) calculated forC₂₈H₃₁ClN₄O₃S 539.1884 (M+H)⁺, found 539.1868.

Example 41

2-[(6-Aminopyridin-3-yl)methyl]-5-3-{[benzyl(methyl)amino]carbonyl}phenyl)-3-mercaptopentanoic acid was synthesised according to theprocedure for Example 26.

¹H NMR (400 MHz, CD₃CN): δ 7.75-7.18 (m, 1 H), 6.88-6.80 (d, 1 H),4.80-4.70 (s, 1 H), 4.53-4.45 (s, 1 H), 3.00-2.95 (m, 1 H), 2.93-2.90(s, 3 H), 2.88-2.78 (m 5 H), 2.05-2.00 (m 1 H), 1.99-1.94 (m, 1 H). HRMS(ESI) calculated for C₂₆H₂₉N₃O₃S 464.2008 (M+H)⁺, found 464.1972.

Example 42

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto5-[3-(pyrrolidin-1-ylcarbonyl)phenyl]pentanoic acid was synthesised according to the procedure forExample 26.

¹H NMR (500 MHz, 95% CD₃CN in D₂O): δ 7.75 (dd, 0.5 H, 7.69 (dd, 0.5 H),7.51-7.54 (m, 1 H), 7.44-7.30 (m, 4 H), 6.91 (d, 0.5 H), 6.87 (d, 0.5H), 3.53 (t, 2 H), 3.30-3.40 (m, 2 H), 3.00-2.79 (m, 5.5 H), 2.67-2.74(m, 0.5 H), 2.18-1.8 (m, 6 H). HRMS (ESI) calculated for C₂₂H₂₈N₃O₃S414.1851 (M+H)⁺, found 414.1837.

Example 43

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[4-(ethoxycarbonyl)piperidin-1-yl]carbonyl}phenyl)-3-mercaptopentanoic acid was synthesised accordingto the procedure for Example 26.

¹H NMR (500 MHz, CD₃CN/D₂O): δ 1.28 (t 3 H), 1.59-1.79 (m, 2 H,1.86-1.96(m, 2 H), 2.0-2.22 (m, 2 H), 2.68-2.75 (m, 1 H), 2.80-3.12 (m,7 H),3.13-3.25 (m, 1 H), 3.65 (d, 1 H), 4.18 (q, 2 H), 4.40-4.48 (m, 1 H),6.95-7.00 (m, 1 H), 7.27-7.31 (m, 2 H), 7.36-7.48 (m, 2 H), 7.60 (s, 1H), 7.78 (dd, 0.5 H), 7.82 (dd, 0.5 H). HRMS (ESI) calculated forC₂₆H₃₄N₃O₅S 500.2219 (M+H)⁺, found 500.2233.

Example 44

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[4hydroxymethyl)piperidin-1-yl]carbonyl}phenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 26.

¹H NMR (400MHz, CD₃CN): δ 7.65-7.71 (dd, 1 H), 7.49-7.52 (d, 1 H),7.18-7.36 (m, 4 H), 6.82-6.85 (dd, 1 H), 3.41-3.47 (m, 4 H), 2.77-3.10(m, 7 H), 2.0-2.1 (m, 2 H), 1.68-1.92 (m, 5 H). HRMS (ESI) calculatedfor C₂₄H₃₂N₃O₄S 458.2114 (M+H)⁺, found 458.2097.

Example 45

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-{3-[(3-oxopiperazin-1-yl)carbonyl]phenyl) pentanoic acid was synthesisedaccording to the procedure for Example 26.

¹H NMR (500 MHz, CD₃CN/D₂O) δ ppm 1.77-1.90 (m, 1 H), 1.99-2.12 (, 1 H),2.75-3.0 (m, 6 H), 3.25-3.58 (m, 4 H), 3.80-4.10 (m, 1 H), 4.2 (s, 1 H),6.89 (d, 0.5 H), 6.91 (d, 0.5 H), 7.24-7.29 (m, 2 H), 7.31-7.42 (m, 2H), 7.52 (s, 1 H), 7.71 (dd, 0.4 H), 7.74 (dd, 0.6 H). HRMS (ESI)calculated for C₂₂H₂₇N₄O₄S 443.1753 (M+H)⁺, found 443.1766.

Example 46

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[benzyl(3-ethoxy-3-oxopropyl)amino]carbonyl}phenyl)3-mercaptopentanoicacid was synthesised according to the procedure for Example 26.

¹H NMR (500 MHz, CD₃CN/D₂O) δ ppm 1.06 (t, 1 H), 1.19 (t, 2 H),1.67-1.88 (m, 1 H), 1.90-2.15 (m, 1 H), 2.40-3.0 (m, 8 E), 3.40-3.58 (m,0.7 H), 3.58-3.66 (m, 1.3 H), 3.91 (q, 0.7 H), 4.07 (q, 1.3 H), 4.47 (s,1.3 H), 4.69 (s, 0.7 H), 6.80-6.92 (m, 1 H), 7.1-7.4 (m, 9 H), 7.46 (s,0.7 H), 7.50 (s, 0.3 H), 7.60-7.74 (m, 1 H). HRMS (ESI) calculated forC₃₀H₃₆N₃O₅S 550.2376 (M+H)⁺, found 550.2361.

Example 47

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[(cyanomethyl)(methyl)amino]-sulfonyl}phenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1, startingfrom N-(cyanomethyl)-3-iodo-N-methylbenzenesulfonamide.N-(cyanomethyl)3-iodo-N-methylbenzenesulfonamide was synthesised from3-iodobenzenesulfonyl chloride using standard procedures.

¹H NMR (500 MHz, CD₃CN/D₂O): δ 7.79 (dd, 0.5 H), 7.76 (dd, 0.5 H),7.74-7.69 (m, 2 H), 7.64-7.54 (m, 3 H), 6.95 (d, 0.5 H), 6.94 (d, 0.5H), 4.29 (s, 2 H), 3.11-3.00 (m, 2 H), 2.86 (s, 3 H), 2.98-2.78 (m, 4H), 2.20-2.09 (m, 1 H), 1.95-1.83 (m, 1 H). HRMS (ES) calculated forC₂₀H₂₅N₂O₄S₂ 449.1317 (M+H)⁺, found 449.1329.

Example 48

2-[(6-Aminopyridin-3-yl)methyl]-5-(3-{[(2S)-2-(anilinomethyl)pyrrolidin-1-yl]sulfonyl}phenyl)-3-mercaptopentanoicacid was synthesised according to the procedure for Example 1, startingfrom N-({(2S)-1-[(3-iodophenyl)sulfonyl]pyrrolidin-2-yl}methyl) aniline.N-({(2S)-1-[(3-iodophenyl)sulfonyl]pyrrolidin-2-yl}methyl)aniline wassynthesised from 3-iodobenzenesulfonyl chloride using standardprocedures.

¹H NMR (500 MHz, CD₃OD): δ 7.71 (dd,J=2.1, 9.1 Hz, 1 H), 7.59-7.45 (m, 7H), 7.31-7.29 (m, 3 H), 6.89 (d,J=9.3 Hz, 1 H), 3.83-3.75 (m, 1 H), 3.53(ddd,J=3.1, 6.0, 13.0 Hz, 1 H), 3.44-3.36 (m, 2 H), 3.26-3.18 (m, 1 H),3.00-2.70 (m, 6 H), 2.05-1.97 (m, 1 H), 1.82-1.65 (m, 3 H), 1.57-1.50(m, 1 H), 1.42-1.32 (m, 1 H). HRMS (ESI) calculated for C₂₈H₃₄N₄O₄S₂555.2100 (M+H)⁺, found 555.2032.

Example 49

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-{3-[(methylamino)sulfonyl]-}pentanoicacid was synthesised according to the procedure for Example 1, startingfrom N-(2-furylmethyl)-3-iodo-N-methylbenzenesulfonamide.N-(2-furylmethyl)-3-iodo-N-methylbenzenesulfonamide was synthesised from3-iodobenzenesulfonyl chloride using standard procedures.

¹H NMR (500 MHz, CD₃OD): δ 7.85 (dd,J=2.1, 9.1 Hz, 1 H), 7.69-7.65 (m, 3H), 7.51-7.50 (m, 2 H), 6.94 (dd,J =0.5, 9.1 Hz, 1 H), 3.12-3.07 (m, 2H), 3.00-2.96 (m, 1 H), 2.93-2.77 (m, 3 H), 2.51(s, 3 H), 2.16-2.10 (m,1 H), 1.91-1.83 (m, 1 H). HRMS (ESI) calculated for C₁₈H₂₃N₃O₄S₂410.1208 (M+H)⁺, found 410.1207.

Example 50

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-(3-{[methyl(2-phenylethyl)amino]sulfonyl}phenyl)pentanoic acid was synthesised according to theprocedure for Example 1, starting from 3-iodo-N-methyl-N-(2-phenylethyl)benzenesulfonamide. 3-iodo-N-methyl-N-(2-phenylethyl)benzenesulfonamidewas synthesised from 3-iodobenzenesulfonyl chloride using standardprocedures.

¹H NMR (400 MHz, CDCl₃): δ 7.64 (s, 1 H), 7.54-7.57 (d, 3 H), 7.39-7.40(d, 3 H), 7.24-7.27 (t, 3 H), 7.14-7.20 (m, 3 H), 6.75 (s, 2 H),3.23-3.27 (t, 2 H), 2.96-3.03 (m, 3 H), 2.80-2.84 (t, 3 H), 2.72 (s, 3H), 2.07 (s, 1 H), 1.69-1.80 (dd, 1 H), 1.53-1.55 (d, 1 H). MS (ESI)514.3 (M+H)⁺.

Example 51

This Example illustrates the preparation of2-[(6-aminopyridin-3-yl)methyl]-3-mercapto-5-[3-(tetrahydrofuran-3-yloxy)phenyl]pentanoic acid.

(a) tert-butyl(3-iodophenoxy)dimethylsilane

Imidazole (7.8 g, 115 mmol) was added to a solution of 3-iodophenol(12.7 g, 58 mmol) and tert-butyl(chloro)dimethylsilane (9.9 g, 65 mmol)in dichloromethane (80 mL) at 0° C. The reaction mixture was stirred atrt overnight. The suspension was washed three times with water and oncewith brine, dried and concentrated to give crudetert-butyl(3-iodophenoxy) dimethylsilane (20 g, 93%).

(b) tert-butyl2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-5-(3-hydroxyphenyl)-3-[(4-methoxybenzyl)thio]pentanoate

Glacial acetic acid (190 μL, 3.3 mmoL) was added to a solution oftert-butyl 2-{6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-5-(3-{[tert-butyl(dimethyl)silyl]oxy}phenyl)-3-[(4-methoxybenzyl)thio]pentanoate(800 mg, 0.89 mmol, synthesised according to the procedure for Example1, starting from tert-butyl(3-iodophenoxy) dimethylsilane) in dry THF(10 mL). Tetrabutylammonium fluoride trihydrate (489 mg, 1.5 mmol) wasadded and the mixture was stirred for 12 h at room temperature. EtOAc(150 mL) was added and the solution was washed with saturated aqueousNaHCO₃, water and brine, dried and concentrated. Flash chromatography(CH₂Cl₂/EtOAc, 10:1) gave tert-butyl2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-5-(3-hydroxyphenyl)-3-[(4-methoxybenzyl)thio]pentanoate (660 mg, 98%).

(c) tert-butyl2-(}6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-[3-(tetrahydrofuran-3-yloxy)phenyl]pentanoate

1,1′-azobis(N,N-dimethylformamide) (134 mg, 0.78 mmol) was added to asolution of tri-n-butylphosphine (221 μL, 0.89 mmol) in toluene (2 mL).Tetrahydrofuran-3-ol (36 μL, 44 mmol) and tert-butyl2-{6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)5-(3-hydroxyphenyl)-3-[(4-methoxybenzyl)thio)pentanoate (154 mg, 0.25 mmol) was added sequentially. The reactionmixture was stirred for 12 h at 80° C. Toluene (100 mL) was added andthe mixture was washed with brine, dried and concentrated. Flashchromatography (toluene/EtOAc, 100:0 to 70:30) gave tert-butyl2-{6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)-3-[(4-methoxybenzyl)thio]-5-[3-(tetrahydrofuran-3-yloxy)phenyl]pentanoate (75 mg, 35%).

(d)2-[(6-aminopyridin-3-yl)methyl]-3-mercapto-5-[3-(tetrahydrofuran-3-yloxy)phenyl]pentanoic acid

2-[(6-aminopyridin-3-yl)methyl]-3-mercapto-5-[3-(tetrahydrofuran-3-yloxy)phenyl]pentanoicacid was synthesised according to the procedure for Example 1, startingfrom tert-butyl2-({6-[(tert-butoxycarbonyl)amino]pyridin-3-yl}methyl)3-[(4methoxybenzyl)thio]-5-[3-(tetrahydrofuran-3-yloxy)phenyl]pentanoate.

¹H NMR (500 MHz, CD₃CN/D₂O (1:1): δ 7.72 (dd, 1 H), 7.53 (d, 1 H), 7.22(dd, 1 H), 6.90 (d, 1 H), 6.83 (d, 1 H), 6.76-6.72 (m, 2 H), 4.98 (m, 1H), 3.93-3.79 (m, 4 H), 2.99-2.84 (m, 3 H), 2.83-2.66 (m, 3 H),2.27-2.18 (m, 1 H), 2.07-1.96 (m, 2 H), 1.83-1.73 (m, 1 H). HRMS (ESI)calculated for C₂₁H₂₇N₂O₄S 403.1692 (M+H)⁺, found 403.1698.

Example 52

2-[(6-Aminopyridin-3-yl)methyl]-3-mercapto-5-[3-(tetrahydrofuran-3-ylmethoxy)-phenyl]pentanoicacid was synthesised according to the procedure for Example 51.

¹H NMR (400 MHz) CD₃CN): δ 7.75-7.69 (d, 1 H), 7.58-7.56 (s, 1 H),7.25-7.18 (m, 1 H), 6.88-6.75 (m, 4 H), 3.98-3.58 (m, 6 H), 3.10-3.00(m, 1 H), 2.95-2.82 (m, 3 H), 2.74-2.65 (m, 2 H), 2.13-2.03 (M, 1 H),1.98-1.66 (m, 4H). MS (ESI) 417.9 (M+H)⁺.

Example 53

The activities of certain Examples in the assay described in: DirkHendriks, Simon Scharpé and Marc van Sande, Clinical Chemistry, 31,1936-1939 (1985) are presented in Table I below. TABLE I Example No.IC₅₀ 6 0.8 μM 7 0.8 μM 11 0.8 μM 18 1.0 μM 24 6.3 μM 25 4.0 μM 28 0.8 μM31 0.6 μM 33 0.6 μM 41 0.6 μM 42 0.6 μM 43 2.0 μM 47 1.0 μM

Abbreviations HOAc = acetic acid HOAc = acetic acid MeOH = methanol MeOH= methanol min = minutes min = minutes rt = room temperature rt = roomtemperature DMF = dimethylformamide TFA = trifluoroacetic acid DMSO =dimethyl sulfoxide THF = tetrahydrofuran EtOAc = ethyl acetate h = hourDBU = 1,8-diazabicyclo[5.4.0]undec-7-ene HATU =O-(7-azabenzotriazol-1-yl)- N,N,N′,N′-tetramethyluroniumhexafluorophosphate

1. A compound of formula (I):

wherein: R¹ is phenyl {optionally substituted by halogen, hydroxy,cyano, C₁₋₄ alkyl (itself optionally mono-substituted by cyano, hydroxyor phenyl), C₁₋₄ alkoxy (itself optionally substituted bytetrahydrofuranyl), CF₃, OCF₃, methylenedioxy, C(O)R³, S(O)₂R⁴ phenyl(itself optionally substituted by halogen), phenoxy (itself optionallysubstituted by halogen) or tetrahydrofuranyloxy}, naphthyl, pyridinyl,1,2,3,4-tetrahydropyrimidin-2,4-dione-yl (optionally substituted by C₁₋₄alkyl) or tetrahydrothienyl; R² is aminopyridinyl, aminothiazolyl or3-azabicyclo[3.2.1]octyl; R³ is hydroxy, C₁₋₄ alkoxy (itself optionallysubstituted by phenyl (itself optionally substituted by halogen) orpyridinyl), NR⁵R⁶ or an N-linked 5- or 6-membered heterocyclic ring{unsubstituted or mono-substituted by hydroxy, oxo, C₁₋₄ alkyl (itselfoptionally substituted by hydroxy or NHphenyl), CO₂(C₁₋₄ alkyl) orphenyl (itself optionally substituted by halogen); R⁴ is NR⁷R⁸ or anN-linked 5- or 6-membered heterocyclic ring {unsubstituted;mono-substituted by hydroxy, oxo, C₁₋₄ alkyl (itself optionallysubstituted by hydroxy or NHphenyl), CO₂(C₁₋₄ alkyl) or phenyl (itselfoptionally substituted by halogen); or fused to a benzene ring which isoptionally substituted by C₁₋₄ alkoxy}; R⁵, R⁶, R⁷ and R⁸ are,independently, hydrogen, C₁₋₄ alkyl {optionally substituted by halogen,cyano, hydroxy, phenyl (itself optionally substituted by halogen ormethylenedioxy), pyridinyl, CO₂H or CO₂(C₁₋₄ alkyl)} I or C₂₋₄ alkenyl;provided that when R² is 6-aminopyridin-3-yl then R¹ is substitutedphenyl, naphthyl, pyridinyl, 1,2,3,4-tetrahydropyrimidin-2,4-dione-yl(optionally substituted by C₁₋₄ alkyl) or tetrahydrothienyl; or apharmaceutically acceptable salt or solvate thereof, or a solvate ofsuch a salt.
 2. A compound of formula (I) as claimed in claim 1 whereinR¹ is phenyl {optionally substituted by halogen, hydroxy, cyano, C₁₋₄alkyl (itself optionally mono-substituted by cyano or hydroxy), C₁₋₄alkoxy, CF₃, OCF₃, methylenedioxy, C(O)NH₂, S(O)₂NH₂ or phenyl (itselfoptionally substituted by halogen)}, pyridinyl or tetrahydrothienyl. 3.A compound of formula (I) as claimed in claim 1 wherein R¹ is phenyl{optionally substituted by halogen, hydroxy, cyano, C₁₋₄ alkyl (itselfoptionally mono-substituted by cyano, hydroxy or phenyl), C₁₋₄ alkoxy,CF₃, OCF₃, methylenedioxy, phenoxy (itself optionally substituted byhalogen), tetrahydrofuranyloxy or tetrahydrofuranylmethoxy}, naphthyl,pyridinyl or tetrahydrothienyl.
 4. A compound of formula (I) as claimedin claim 1 wherein R¹ is phenyl {substituted by halogen, hydroxy, cyano,C₁₋₄ alkyl (itself optionally mono-substituted by cyano or hydroxy),C₁₋₄ alkoxy, CF₃ or methylenedioxy} or tetrahydrothiophenyl.
 5. Acompound of formula (I) as claimed in claim 1, 2, 3 or 4 wherein R² is 6aminopyridin-3-yl, 2-aminothiazol-5-yl or 3-azabicyclo[3.2.1]oct-8-yl.6. A compound of formula (I) as claimed in claim 1, 2, 3 or 4 wherein R²is 6aminopyridin3-yl.
 7. A process for preparing a compound of formula(I) comprising reacting a compound of formula (II):

wherein R¹ is as defined in claim 1 or includes a group that can besubsequently reacted to form the group R¹ R* is a suitable protectinggroup and R² is as defined in claim 1 or the amine function of R² can beprotected, with a thiol of formula L-SH, wherein L is a suitableprotecting group, in the presence of a suitable catalyst and in asuitable solvent, to form a compound of formula (III):

and, optionally reacting the functional group on R¹, and subsequentlyremoving the protecting groups as necessary.
 8. A pharmaceuticalformulation containing a compound according to any one of claims 1 to 6as active ingredient in combination with a pharmaceutically acceptableadjuvant, diluent or carrier.
 9. The use of a compound as claimed inclaim 1 in therapy.
 10. The use of a compound as claimed in claim 1 forthe manufacture of a medicament for the inhibition of carboxypeptidaseU.
 11. A method for treatment or prophylaxis of conditions whereinhibition of carboxypeptidase U is beneficial, comprising administeringto a mammal, including man, in need of such treatment an effectiveamount of a compound as claimed in claim
 1. 12. A pharmaceuticalformulation for use in the treatment or prophylaxis of conditions whereinhibition of carboxypeptidase U is beneficial, comprising a compound asclaimed in claim 1 in combination with a pharmaceutically acceptableadjuvant, diluent or carrier.